One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(9,10,14,15)(11,13,18,16)(12,20,22,17)(19,23,24,21)(27,33)(28,36)(31,34)(32,37)(1,2,4,6)(3,5,8,7)(10,15)(11,18)(17,20)(19,24)(25,26,30,29)(27,34,33,31)(28,32,36,37)(35,40,39,38)(1,2)(3,5)(4,6)(7,8)(9,10)(11,16)(12,17)(13,18)(14,15)(19,23)(20,22)(21,24)(25,27)(26,31)(28,35)(29,34)(30,33)(32,38)(36,39)(37,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,14,18)(10,16,15,13)(12,19,22,24)(17,23,20,21)(9,12,14,22)(10,17,15,20)(11,19,18,24)(13,21,16,23)(25,28,30,36)(26,32,29,37)(27,35,33,39)(31,38,34,40)(9,13,14,16)(10,18,15,11)(12,21,22,23)(17,24,20,19)(25,29,30,26)(27,31,33,34)(28,37,36,32)(35,38,39,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.